I bought an 85 Jazz special - some of the controls were a little funky - but the price was good. I know next to nothing about electronics except to solder a part in place. The bass has 3 knobs and 1 3 way switch. What should each control do ? It appears that someone added an active system - The first knob is the pull up type - when it is down - it is passive - when it is pulled up - it is active ( and won't work without a battery). The 3 way is disconnected from everything - the 2nd pot need to be replaced - it just keeps turning and the last pot doesn't seem to do anything. How should the electronics on this bass be ? I am going to replace it back to original - which I am assuming from things I have read that it was a passive bass originally. Any input would help. BTW - it plays great - and sounds good in passive mode !